This invention relates to a rapidly hydrating xanthan gum and rapidly hydrating guar gum, and processes for their preparation. This invention also relates to a process for sterilizing food products containing xanthan gum or guar gum as a thickening hydrocolloid. Other aspects of the disclosed invention as well as its advantages will be apparent to those ordinarily skilled in the art upon reading the following disclosure and claims.
Hydrophilic polymers or gums are widely used in industry. They are used commercially to thicken, suspend or stabilize aqueous systems. They are also used to produce gels or act as emulsion stabilizers, flocculants, binders, film formers, lubricants and friction reducers. In other words, they act to adjust and control the rheological properties of the aqueous systems to which they are added.
One of the most widely used gums in industry is xanthan gum. Xanthan gum is an extracellularly produced gum made by the heteropolysaccharide-producing bacterium Xanthomonas campestris by whole culture fermentation of a medium comprising a fermentable carbohydrate, a nitrogen source and other appropriate nutrients. Examples of commercially available xanthan gum are KELTROL T, KELTROL F, KELZAN AR and KELZAN, available from Kelco Division of Merck & Co., Inc. Processes for producing xanthan gum are described in a number of patents, including U.S. Pat. Nos. 4,316,012, 4,352,882 and 4,375,512.
Previous methods employed to improve the hydration rate of xanthan gum, freeze drying and agglomeration, gave only a slight increase in hydration rate and resulted in a diluted sample. It has now been found that by treating the xanthan gum powder with ionizing radiation, one can increase the hydration rate of xanthan gum by as much as 90%. This allows for faster solution preparation times, i.e., faster addition of dry polymer to aqueous systems, thereby increasing productivity. Productivity is increased because shorter mixing times are needed to achieve 100% hydration. The present invention on the other hand is a one step process yielding a 100% gum product with a hydration rate that is up to 90% greater than that of an untreated gum.
Treatment of polymers such as arabinoxylan and karaya gum with ionizing radiation (e.g., gamma irradiation) is disclosed in the prior art. However, these publications do not teach or suggest treatment of xanthan gum with ionizing radiation to increase the hydration rate. Nor do they teach or suggest sterilization of food products containing xanthan gum therein. The Journal of Applied Polymer Science, vol. 38, 1919-1928 (1989), discloses only that the effect of gamma irradiation on a water-insoluble arabinoxylan is to modify both sugar components of the arabinoxylan, thus increasing the molecular and chemical heterogeneity of the polysaccharide. It has also been shown that the microbiological contamination of Karaya gum from Sterculia urens and S. setigera, resulting in part from the mode of storage and handling, can be greatly reduced by radiosterilization of powered samples. Food Hydrocolloids, vol. 5 no. 1/2, 155-157 (1991).